The electric switches intended to initiate critical functions, used for example on aircraft instrument panels, must satisfy a certain number of constraints. Notably, certain functions require their operation to be effected via pressure on a switch that is redundant from an electrical point of view, that is to say, a switch that simultaneously establishes the electric contact for at least two electric circuits implementing, for example, a single function, the two electric circuits having no common electric mode. Such is, for example, the case in aircraft, for the switches initiating an automatic pilot device. For such applications, it is also preferable for the switches positioned on the instrument panel to be of compact structure. Furthermore, it is desirable for the tactile sensation provided to a user by the switch on an action thereon to be pleasant, and provide feedback information enabling the user to confirm the correct accomplishment of the action initiated.
Pushbutton switches of the “dome” switch type, often simply called “dome switches” are notably commonly used in aircraft instrument panels. In this type of switch, the electric switching is performed by the depression or “deflection” of a conductive elastic blister dome against two conductors to be linked together. The dome switches are not intrinsically provided with systems for ensuring the electrical redundancy; however, there are solutions known in the art, for secured dome switches. Notably, according to one known technique, a switch makes it possible, by a mechanical action, to activate two electric contacts positioned one alongside the other and activated by one and the same surface of the switch. The assembly may form a pushbutton switch that can be mounted, for example, on the front of an instrument panel, for example by soldering. A drawback associated with this technical solution lies in the fact that producing such a switch is difficult, in as much as the two electric contacts have to be activated simultaneously. The simultaneous activation of the two electric contacts is all the more difficult when the pushbutton of the switch is pressed on the edges or else on the crest thereof. In fact, in such a case, it is possible for only one contact of the two to be made. It is possible to overcome this drawback by equipping the switch with accurate guiding devices, but to the detriment of the cost of manufacture and to the price of spurious friction effects detrimental to the comfort of the user. Furthermore, the guiding systems may lead to problems caused by the switch becoming jammed, due, for example, to bracing effects.